1. Field of the Invention
This invention relates to coiled disk springs used as a support for machines and appliances. More particularly, the present invention relates to a coiled disk spring formed by closely winding a deformed wire or a strip into a coil shape with the face of the wire or strip inclined with respect to the coil axis and further to a coiled disk spring obtained by undulating this coiled disk spring in a circumferential direction of the coil.
2. Description of the Prior Art
Disk springs have heretofore been used as support springs for machines and appliances in which a plurality of disk springs 2 are stacked up in parallel with one another, as shown in FIG. 8, so that the restoring force as springs is increased.
However, in the production of disk springs, since a sheet material must be punched out by a press, there is such a problem that the yield of the material is low and the production cost is high.
When the sheet material is punched out by the press, the resulting springs can only have a predetermined thickness.
Further, when the disk springs are assembled into a stack 3 by stacking up the springs, mistakes are likely to occur, such as variations in the number of disk springs to be stacked up or mixing of inverted pieces in the stack.
A coiled wave spring as shown in FIGS. 9 and 10 has also been employed. This spring is produced by closely winding a strip 5 into a coil shape while bending the strip into a wavy form 6 in the circumferential direction of the coil as shown in FIG. 10.
When a load in the vertical direction is applied to this coiled wave spring, the wavy form 6 deforms flat, so that elasticity develops and gives a supporting force to the load.
The load-deflection characteristics of a conventional coiled wave spring are shown by the dashed line A in FIG. 7. As shown in the drawing, this wave spring exhibits linear characteristics such that the load and deflection are proportional to each other.
In order to obtain nonlinear characteristics (hereinafter, referred to as "progressive nonlinear characteristics") providing large flexibility at the initial load and small flexibility at a large load, at least two kinds of springs must be combined with one another.